The power supply market has been opened as a result of the deregulation of electric utilities, and a power user (consumer) can now supply power not only to general electricity utilities (power companies), but also to specified-scale electricity utilities (electricity utilities). As compared to a power company, however, an electricity utility does not have a large-scale power generation facility or power transmission facility and often does not have a power transmission facility at all. Therefore, since an electricity utility operates while borrowing the facilities of a power company, the electricity utility is required to notify the power company in advance of a planned consumption value (planned value) of power that customers are expected to consume the following day and is required to supply power commensurate with the planned value using the electricity utility's own power generation and separately procured power.
In general, the demand for power on the consumer's side depends not only on the consumer's daily activities but also varies greatly with changes in weather conditions, sudden events, and the like. Due to such weather changes and sudden events, there may be a large difference between the planned value and the actual usage value. In this case, an electricity utility that does not have a large-scale power generation facility incurs a power supply shortage due to a small reserve power supply. Even if a power supply shortage occurs, power from the power company is supplied to the consumer when the power company's power grid is under lease, and therefore the consumer does not suffer from a power shortage. The electricity utility, however, is charged an expensive compensatory payment by the power company. Such compensatory payments are one factor that places a strain on the management of electricity utilities.